possible deadlock in get_user_pages_unlocked (2)

[syzbot]

syzbot has bisected this bug to:

commit 69d61f577d147b396be0991b2ac6f65057f7d445
Author: Mimi Zohar <zohar at linux.ibm.com>
Date:   Wed Apr 3 21:47:46 2019 +0000

     ima: verify mprotect change is consistent with mmap policy

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=1055a2f2a00000
start commit:   56b697c6 Add linux-next specific files for 20190604
git tree:       linux-next
final crash:    https://syzkaller.appspot.com/x/report.txt?x=1255a2f2a00000
console output: https://syzkaller.appspot.com/x/log.txt?x=1455a2f2a00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=4248d6bc70076f7d
dashboard link: https://syzkaller.appspot.com/bug?extid=e1374b2ec8f6a25ab2e5
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=165757eea00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10dd3e86a00000

Reported-by: syzbot+e1374b2ec8f6a25ab2e5 at syzkaller.appspotmail.com
Fixes: 69d61f577d14 ("ima: verify mprotect change is consistent with mmap  
policy")

For information about bisection process see: https://goo.gl/tpsmEJ#bisection